Technical Field
The present disclosure relates to a semiconductor device and a method of manufacturing the same, and more particularly to a semiconductor device having a nitride-based high electron mobility transistors (HEMTs) and its manufacturing method.
Description of Related Art
HEMT is a device used in high power and/or high frequency operation. These devices use the spontaneous polarization and the piezo polarization to induce two dimensional electron gas (2DEG) in the heterojunction of two semiconductor material which have different bandgap energies.
AlGaN and GaN are usually applied in typical HEMT devices. The 2DEG increases with the increase in Al composition of the AlGaN. However, since AlGaN material shows a large lattice mismatching against GaN, the increase of Al composition may cause crack to occur at the interface. Another type HEMT device use AlInN instead of AlGaN, since AlInN has many advantages compared to AlGaN. For example, AlInN is in the lattice constant thereof matches with GaN, and thus crack or the like that will degrade the performance of the HEMT device will not occur; AlInN has higher spontaneous polarization and higher conduction band energy discontinuity, thus 2DEG will increase at the interface.
However the electron mobility and breakdown voltage of AlInN-based HEMT devices are still inferior to the AlGaN-based HEMT devices. Owing to the large difference in dissociation temperature between AlN and InN, it is difficult in preparing a high-quality AlInN layer. The resultant alloy scattering and interface roughness scattering will deteriorate electron mobility. Besides, the strong polarization field in the AlInN layer could enhance tunneling current and lead to high gate leakage current and low breakdown voltage. Therefore, a solution is urgently needed to improve the AlInN-based HEMT device.